Tham khảo tài liệu 'marine auxiliary machinery 7e episode 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 310 Steering gears Figure Hydraulic circuit diagram for hand and power steering. For key to letters see text Steering gear with constant output pump A steering gear as with any hydraulic system can be operated by a constant delivery pump as an alternative to the conventional variable delivery type. Output from the pump which runs continuously is circulated through a bypass until required for steering gear movement. Small hand and power gears A simpler variant of the electro-hydraulic gear for small ships requiring rudder torques below say 150 kNm is shown in Figure . The hydraulic circuit is shown diagrammatically in Figure . The rams Ư in the double-acting steering cylinders G which are free to oscillate on chocked trunnions are linked directly to the tiller. F is a double-acting control cylinder linked to the floating lever V by rod o. J is a directional control valve linked to the mid point of the floating lever by a spring link z. w is the cut-off link from tiller to floating lever. H is a locking valve and I a bypass valve. Valves c D and s are solenoid controlled. When not energized c is open and D is closed to through flow but acts as a bypass between the ends of control cylinder F when solenoid s is closed. When the solenoids are energized c is closed D and s are open. J is only operative when steering by power. When steering by hand c D and s are not energized. A pump B in the steering pedestal coupled to the wheel deliver fluid under pressure direct to steering gears 311 the steering cylinders G so moving the tiller in the sense and to the extent appropriate to the movement of the wheel. There is no hunting action. To change to power steering the power pump is started and c D and s are energized . c is closed D ceases to be a bypass and it connects the steering pedestal pump to the control cylinder F. s now open allows fluid to pass from the power pump to J which now comes under the influence of the floating lever. Steering-wheel movement
